The privileged few who study one of the world's most notorious viruses now have an unfamiliar luxury: boundless time. On 18 May, the World Health Organization's (WHO's) top decision-making body approved a recommendation to delay destruction of the world's two known stocks of smallpox, held under tight guard in Russia and the United States. And, to the surprise of many at last week's meeting of the World Health Assembly (WHA) in Geneva, anticipated calls for a new destruction date failed to materialize.

A year ago, WHO was poised to approve incineration of the stocks--the last known samples of live virus after the disease was eradicated from the wild--by the end of 2002. But the 11 September attacks, followed by the anthrax-tainted letter campaign, heightened fears that smallpox could be resurrected from clandestine stocks or, less plausibly, diverted from the two sanctioned stocks. Those disturbing scenarios prompted WHO's governing board last January to recommend extending the virus's stay on death-row. The reprieve could permit Russia, the United States, and collaborating countries to develop modern diagnostics, safer vaccines, and drugs against the disease (Science, 15 March, p. 2001[2]).

The WHA's imprimatur allows this loosely coordinated program to shift into high gear. "For scientists, it's really good news," says Antonio Alcami of the University of Cambridge, U.K., a mousepox expert and WHO adviser. He notes that potential smallpox studies--part of a batch of biodefense projects that a U.S. National Institute of Allergy and Infectious Diseases panel will review for funding next month--could now proceed with confidence that any promising vaccines or drugs they turn up could be pitted against live virus.

Indeed, smallpox researchers may have more breathing space than expected. Last January, China's Permanent Representative to the United Nations in Geneva, Sha Zukang, implored the agency to set a new date for destruction (Science, 25 January, p. 598[3]). China backed off this demand at the WHA meeting. According to Lev Sandakhchiev, director of the Russian smallpox repository in Koltsovo, this "may mean that we have another 5 to 7 years [of research] ahead of us."